研究者詳細 - 曽我　朋義

論文 - 曽我　朋義

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Energy-sparing by 2-methyl-2-thiazoline protects heart from ischaemia/reperfusion injury

Nishi M., Ogata T., Kobayakawa K., Kobayakawa R., Matsuo T., Cannistraci C.V., Tomita S., Taminishi S., Suga T., Kitani T., Higuchi Y., Sakamoto A., Tsuji Y., Soga T., Matoba S.

ESC Heart Fail. 9 （ 1 ） 428 - 441 2022年02月

研究論文（学術雑誌）, 共著, 査読有り

Aims: Cardiac ischaemia/reperfusion (I/R) injury remains a critical issue in the therapeutic management of ischaemic heart failure. Although mild hypothermia has a protective effect on cardiac I/R injury, more rapid and safe methods that can obtain similar results to hypothermia therapy are required. 2-Methyl-2-thiazoline (2MT), an innate fear inducer, causes mild hypothermia resulting in resistance to critical hypoxia in cutaneous or cerebral I/R injury. The aim of this study is to demonstrate the protective effect of systemically administered 2MT on cardiac I/R injury and to elucidate the mechanism underlying this effect. Methods and results: A single subcutaneous injection of 2MT (50 mg/kg) was given prior to reperfusion of the I/R injured 10 week-old male mouse heart and its efficacy was evaluated 24 h after the ligation of the left anterior descending coronary artery. 2MT preserved left ventricular systolic function following I/R injury (ejection fraction, %: control 37.9 ± 6.7, 2MT 54.1 ± 6.4, P < 0.01). 2MT also decreased infarct size (infarct size/ischaemic area at risk, %: control 48.3 ± 12.1, 2MT 25.6 ± 4.2, P < 0.05) and serum cardiac troponin levels (ng/mL: control 8.9 ± 1.1, 2MT 1.9 ± 0.1, P < 0.01) after I/R. Moreover, 2MT reduced the oxidative stress-exposed area within the heart (%: control 25.3 ± 4.7, 2MT 10.8 ± 1.4, P < 0.01). These results were supported by microarray analysis of the mouse hearts. 2MT induced a transient, mild decrease in core body temperature (°C: −2.4 ± 1.4), which gradually recovered over several hours. Metabolome analysis of the mouse hearts suggested that 2MT minimized energy metabolism towards suppressing oxidative stress. Furthermore, 18F-fluorodeoxyglucose-positron emission tomography/computed tomography imaging revealed that 2MT reduced the activity of brown adipose tissue (standardized uptake value: control 24.3 ± 6.4, 2MT 18.4 ± 5.8, P < 0.05). 2MT also inhibited mitochondrial respiration and glycolysis in rat cardiomyoblasts. Conclusions: We identified the cardioprotective effect of systemically administered 2MT on cardiac I/R injury by sparing energy metabolism with reversible hypothermia. Our results highlight the potential of drug-induced hypothermia therapy as an adjunct to coronary intervention in severe ischaemic heart disease.

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Group IIA secreted phospholipase A2 controls skin carcinogenesis and psoriasis by shaping the gut microbiota

Miki, Y., Taketomi, Y., Kidoguchi, Y., Yamamoto, K., Muramatsu, K., Nishito, Y., Park, J., Hosomi, K., Mizuguchi, K., Kunisawa, J., Soga, T., Boilard, E., Gowda, S.G.B. Ikeda, K., Arita, M., Murakami, M.

JCI Insight 7 （ 2 ） e152611 2022年01月

研究論文（学術雑誌）, 共著, 査読有り

Besides promoting inflammation by mobilizing lipid mediators, group IIA secreted phospholipase A2 (sPLA2-IIA) prevents bacterial infection by degrading bacterial membranes. Here, we show that, despite the restricted intestinal expression of sPLA2-IIA in BALB/c mice, its genetic deletion leads to amelioration of cancer and exacerbation of psoriasis in distal skin. Intestinal expression of sPLA2-IIA is reduced after treatment with antibiotics or under germ-free conditions, suggesting its upregulation by gut microbiota. Metagenome, transcriptome, and metabolome analyses have revealed that sPLA2-IIA deficiency alters the gut microbiota, accompanied by notable changes in the intestinal expression of genes related to immunity and metabolism, as well as in the levels of various blood metabolites and fecal bacterial lipids, suggesting that sPLA2-IIA contributes to shaping of the gut microbiota. The skin phenotypes in Pla2g2a-/- mice are lost (a) when they are cohoused with littermate WT mice, resulting in the mixing of the microbiota between the genotypes, or (b) when they are housed in a more stringent pathogen-free facility, where Pla2g2a expression in WT mice is low and the gut microbial compositions in both genotypes are nearly identical. Thus, our results highlight a potentially new aspect of sPLA2-IIA as a modulator of gut microbiota, perturbation of which affects distal skin responses.

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Glucocorticoid imprints a low glucose metabolism onto CD8 T cells and induces the persistent suppression of the immune response

Konishi, A., Suzuki, J., Kuwahara, M., Matsumoto, A., Nomura, S., Soga, T., Yorozuya, T., Yamashita, M.

Biochem. Biophys. Res. Commun. 588 34 - 40 2022年01月

共著, 査読有り, ISSN 0006291X

Glucocorticoids (GCs), immunosuppressive, and anti-inflammatory agents have various effects on T cells. However, the long-term influence of GCs on the T cell-mediated immune response remain to be elucidated. We demonstrated that the administration of GC during the TCR-mediated activation phase induced long-lasting suppression of glycolysis, even after the withdrawal of GC. The acquisition of the effector functions was inhibited, while the expression of PD-1 was increased in CD8 T cells activated in the presence of GC. Furthermore, adoptive transfer experiments revealed that GC-treated CD8 T cells reduced memory T cell formation and anti-tumor activity. These findings reveal that GCs have long-lasting influence on the T cell-mediated immune response via modulation of T cell metabolism.

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Hao1 Is Not a Pathogenic Factor for Ectopic Ossifications but Functions to Regulate the TCA Cycle In Vivo

Kimura, A., Hirayama, A., Matsumoto, T., Sato, Y., Kobayashi, T., Ikeda, S., Maruyama, M., Kaneko, M., Shigeta, M., Ito, E., Soma, T., Miyamoto, K., Soga, T., Tomita, M., Oya, A., Matsumoto, M., Nakamura, M., Kanaji, A., Miyamoto, T.

Metabolites 12 （ 1 ） 82 2022年01月

研究論文（学術雑誌）, 共著, 査読有り

Ossification of the posterior longitudinal ligament (OPLL), a disease characterized by the ectopic ossification of a spinal ligament, promotes neurological disorders associated with spinal canal stenosis. While blocking ectopic ossification is mandatory to prevent OPLL development and progression, the mechanisms underlying the condition remain unknown. Here we show that expression of hydroxyacid oxidase 1 (Hao1), a gene identified in a previous genome-wide association study (GWAS) as an OPLL-associated candidate gene, specifically and significantly decreased in fibroblasts during osteoblast differentiation. We then newly established Hao1-deficient mice by generating Hao1-flox mice and crossing them with CAG-Cre mice to yield global Hao1-knockout (CAG-Cre/Hao1flox/flox; Hao1 KO) animals. Hao1 KO mice were born normally and exhibited no obvious phenotypes, including growth retardation. Moreover, Hao1 KO mice did not exhibit ectopic ossification or calcification. However, urinary levels of some metabolites of the tricarboxylic acid (TCA) cycle were significantly lower in Hao1 KO compared to control mice based on comprehensive metabolomic analysis. Our data indicate that Hao1 loss does not promote ectopic ossification, but rather that Hao1 functions to regulate the TCA cycle in vivo.

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SI-MOIRAI: A new method to identify and quantify the metabolic fate of nucleotides

Ikeda, Y., Hirayama, A., Kofuji, S., Hirota, Y., Kamata, R., Osaka, N., Fujii, Y., Sasaki, M., Ikeda, S., Smith, E.P., Bachoo, R., Soga, T., Sasaki, A.T.

J Biochem. 170 （ 6 ） 699 - 711 2022年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0021924X

Since the discovery of nucleotides over 100 years ago, extensive studies have revealed the importance of nucleotides for homeostasis, health, and disease. However, there remains no established method to investigate quantitively and accurately intact nucleotide incorporation into RNA and DNA. Herein, we report a new method, Stable-Isotope Measure Of Influxed Ribonucleic Acid Index (SI-MOIRAI), for the identification and quantification of the metabolic fate of ribonucleotides and their precursors. SI-MOIRAI, named after Greek goddesses of fate, combines a stable isotope-labeling flux assay with mass spectrometry to enable quantification of the newly synthesized ribonucleotides into r/m/tRNA under a metabolic stationary state. Using glioblastoma U87MG cells and a patient-derived xenograft (PDX) glioblastoma mouse model, SI-MOIRAI analyses showed that newly synthesized GTP was particularly and disproportionally highly utilized for rRNA and tRNA synthesis but not for mRNA synthesis in glioblastoma (GBM) in vitro and in vivo. Furthermore, newly synthesized pyrimidine nucleotides exhibited a significantly lower utilization rate for RNA synthesis than newly synthesized purine nucleotides. The results reveal the existence of discrete pathways and compartmentalization of purine and pyrimidine metabolism designated for RNA synthesis, demonstrating the capacity of SI-MOIRAI to reveal previously unknown aspects of nucleotide biology.

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Stemness and immune evasion conferred by TDO2-AHR pathway are associated with liver metastasis of colon cancer

Miyazaki, T., Chung, S., Sakai, H., Ohata, H., Obata, Y., Shiokawa, D., Mizoguchi, Y., Kubo, T., Ichikawa, H., Taniguchi, H., Aoki, K., Soga, T., Nakagama, H., Okamoto, K.

Cancer Sci. 113 （ 1 ） 170 - 181 2022年01月

研究論文（学術雑誌）, 共著, 査読有り

The aryl hydrocarbon receptor (AHR) pathway modulates the immune system in response to kynurenine, an endogenous tryptophan metabolite. IDO1 and TDO2 catalyze kynurenine production, which promotes cancer progression by compromising host immunosurveillance. However, it is unclear whether the AHR activation regulates the malignant traits of cancer such as metastatic capability or cancer stemness. Here, we carried out systematic analyses of metabolites in patient-derived colorectal cancer spheroids, and identified high levels of kynurenine and TDO2 that were positively associated with liver metastasis. In a mouse colon cancer model, TDO2 expression substantially enhanced liver metastasis, induced AHR-mediated PD-L1 transactivation, and dampened immune responses; these changes were all abolished by PD-L1 knockout. In patient-derived cancer spheroids, TDO2 or AHR activity was required for not only the expression of PD-L1, but also for cancer stem cell (CSC)-related characteristics and Wnt signaling. TDO2 was coexpressed with both PD-L1 and nuclear β-catenin in colon xenograft tumors, and the coexpression of TDO2 and PD-L1 was observed in clinical colon cancer specimens. Thus, our data indicate that the activation of the TDO2-kynurenine-AHR pathway facilitates liver metastasis of colon cancer via PD-L1-mediated immune evasion and maintenance of stemness.

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Metabolic profiling of charged metabolites in association with menopausal status in Japanese community-dwelling midlife women: Tsuruoka Metabolomic Cohort Study

Watanabe, K., Iida, M., Harada, S., Kato, S., Kuwabara, K., Kurihara, A., Takeuchi, A., Sugiyama, D., Okamura, T., Suzuki, A., Amano, K., Hirayama, A., Sugimoto, M., Soga, T., Tomita, M., Kobayashi, Y., Banno, K., Aoki, D., Takebayashi, T.

Maturitas 155 54 - 62 2022年01月

研究論文（学術雑誌）, 共著, 査読有り

Background
Emerging evidence has shown that charged metabolites, such as amino acids, may play an important role in the pathogenesis of various metabolic disorders, many of which women in the postmenopausal period are at high risk of developing. This study examined the metabolic profile of middle-aged Japanese women to investigate alterations in charged metabolites induced by menopausal transition.

Methods
The participants were 1193 female residents aged 40–60 at the baseline survey of the Tsuruoka Metabolomics Cohort Study. We investigated the cross-sectional association of menopausal status with 94 metabolomic biomarkers assayed in fasting plasma samples via capillary electrophoresis time-of-flight mass spectrometry using linear regression analysis.

Results
Among the participants, 529 were premenopausal, 132 were in menopausal transition (MT), and 532 were postmenopausal. Significant differences were found in age, blood pressure, glucose and lipid levels, and smoking and drinking habits among the three groups. The concentrations of 5 metabolites in the MT group and 15 metabolites in the postmenopausal group were significantly higher than those in the premenopausal group after adjusting for confounding factors. When classified into pathways, these metabolites were related to the tricarboxylic cycle, urea cycle, and homocysteine metabolism, some of which are linked to arteriosclerosis.

Conclusion
Multiple charged metabolites were associated with women's menopausal status, showing a gradual increase as women shifted from pre-, to peri-, to postmenopause. These findings might reflect the early changes behind the increased risk of dyslipidemia, diabetes, cardiovascular disease, and osteoporosis in later life.

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MEK inhibition preferentially suppresses anchorage-independent growth in osteosarcoma cells and decreases tumors in vivo

Shimizu, T., Kimura, K., Sugihara, E., Yamaguchi-Iwai, S., Nobuse, H., Sampetrean, O., Otsuki, Y., Fukuchi, Y., Saitoh, K., Kato, K., Soga, T., Muto, A., Saya, H.

J. Orthop. Res. 39 （ 12 ） 2732 - 2743 2021年12月

研究論文（学術雑誌）, 共著, 査読有り

Osteosarcoma is the most common high-grade malignancy of bone, and novel therapeutic options are urgently required. Previously, we developed mouse osteosarcoma AXT cells that can proliferate both under adherent and nonadherent conditions. Based on metabolite levels, nonadherent conditions were more similar to the in vivo environment than adherent conditions. A drug screen identified MEK inhibitors, including trametinib, that preferentially decreased the viability of nonadherent AXT cells. Trametinib inhibited the cell cycle and induced apoptosis in AXT cells, and both effects were stronger under nonadherent conditions. Trametinib also potently decreased viability in U2OS cells, but its effects were less prominent in MG63 or Saos2 cells. By contrast, MG63 and Saos2 cells were more sensitive to PI3K inhibition than AXT or U2OS cells. Notably, the combination of MAPK/ERK kinase (MEK) and PI3K inhibition synergistically decreased viability in U2OS and AXT cells, but this effect was less pronounced in MG63 or Saos2 cells. Therefore, signal dependence for cell survival and crosstalk between MEK-ERK and PI3K-AKT pathways in osteosarcoma are cell context-dependent. The activation status of other kinases including CREB varied in a cell context-dependent manner, which might determine the response to MEK inhibition. A single dose of trametinib was sufficient to decrease the size of the primary tumor and circulating tumor cells in vivo. Moreover, combined administration of trametinib and rapamycin or conventional anticancer drugs further increased antitumor activity. Thus, given optimal biomarkers for predicting its effects, trametinib holds therapeutic potential for the treatment of osteosarcoma.

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Identification of the first highly selective inhibitor of human lactate dehydrogenase B

Shibata, S., Sogabe, S., Miwa, M., Fujimoto, T., Takakura, N., Naotsuka, A., Kitamura, S., Kawamoto, T., Soga, T.

Sci Rep. 11 （ 1 ） 21353 2021年11月

研究論文（学術雑誌）, 共著, 査読有り

Lactate dehydrogenase (LDH) catalyses the conversion of pyruvate to lactate and NADH to NAD+; it has two isoforms, LDHA and LDHB. LDHA is a promising target for cancer therapy, whereas LDHB is necessary for basal autophagy and cancer cell proliferation in oxidative and glycolytic cancer cells. To the best of our knowledge, selective inhibitors for LDHB have not yet been reported. Here, we developed a high-throughput mass spectrometry screening system using an LDHB enzyme assay by detecting NADH and NAD+. As a result, we identified a small-molecule LDHB selective inhibitor AXKO-0046, an indole derivative. This compound exhibited uncompetitive LDHB inhibition (EC50 = 42 nM). X-ray crystallography revealed that AXKO-0046 bound to the potential allosteric site away from the LDHB catalytic active site, suggesting that targeting the tetramerisation interface of the two dimers is critical for the enzymatic activity. AXKO-0046 and its derivatives can be used to validate LDHB-associated pathways in cancer metabolism.

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Basigin deficiency prevents anaplerosis and ameliorates insulin resistance and hepatosteatosis

Ryuge, A., Kosugi, T., Maeda, K., Banno, R., Gou, Y., Zaitsu, K., Ito, T., Sato, Y., Hirayama, A., Tsubota, S., Honda, T., Nakajima, K., Ozaki, T., Kondoh, K., Takahashi, K., Kato, N., Ishimoto, T., Soga, T., Nakagawa, T., Koike, T., Arima, H., Yuzawa, Y., Minokoshi, Y., Maruyama, S., Kadomatsu, K.

JCI Insight 6 （ 20 ） e142464 2021年10月

研究論文（学術雑誌）, 共著, 査読有り

Monocarboxylates, such as lactate and pyruvate, are precursors for biosynthetic pathways, including those for glucose, lipids, and amino acids via the tricarboxylic acid (TCA) cycle and adjacent metabolic networks. The transportation of monocarboxylates across the cellular membrane is performed primarily by monocarboxylate transporters (MCTs), the membrane localization and stabilization of which are facilitated by the transmembrane protein basigin (BSG). Here, we demonstrate that the MCT/BSG axis sits at a crucial intersection of cellular metabolism. Abolishment of MCT1 in the plasma membrane was achieved by Bsg depletion, which led to gluconeogenesis impairment via preventing the influx of lactate and pyruvate into the cell, consequently suppressing the TCA cycle. This net anaplerosis suppression was compensated in part by the increased utilization of glycogenic amino acids (e.g., alanine and glutamine) into the TCA cycle and by activated ketogenesis through fatty acid β-oxidation. Complementary to these observations, hyperglycemia and hepatic steatosis induced by a high-fat diet were ameliorated in Bsg-deficient mice. Furthermore, Bsg deficiency significantly improved insulin resistance induced by a high-fat diet. Taken together, the plasma membrane-selective modulation of lactate and pyruvate transport through BSG inhibition could potentiate metabolic flexibility to treat metabolic diseases.

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Urinary metabolome analyses of patients with acute kidney injury using capillary electrophoresis-mass spectrometry

Saito R., Hirayama A., Akiba A., Kamei Y., Kato Y., Ikeda S., Kwan B., Pu M., Natarajan L., Shinjo H., Akiyama S., Tomita M., Soga T., Maruyama S.

Metabolites 11 （ 10 ） 671 2021年09月

研究論文（学術雑誌）, 共著, 査読有り

Acute kidney injury (AKI) is defined as a rapid decline in kidney function. The associated syndromes may lead to increased morbidity and mortality, but its early detection remains difficult. Using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS), we analyzed the urinary metabolomic profile of patients admitted to the intensive care unit (ICU) after invasive surgery. Urine samples were collected at six time points: before surgery, at ICU admission and 6, 12, 24 and 48 h after. First, urine samples from 61 initial patients (non-AKI: 23, mild AKI: 24, severe AKI: 14) were measured, followed by the measurement of urine samples from 60 additional patients (non-AKI: 40, mild AKI: 20). Glycine and ethanolamine were decreased in patients with AKI compared with non-AKI patients at 6–24 h in the two groups. The linear statistical model constructed at each time point by machine learning achieved the best performance at 24 h (median AUC: 89%, cross-validated) for the 1st group. When cross-validated between the two groups, the AUC showed the best value of 70% at 12 h. These results identified metabolites and time points that show patterns specific to subjects who develop AKI, paving the way for the development of better biomarkers.

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Upregulation of Thymidylate Synthase Induces Pemetrexed Resistance in Malignant Pleural Mesothelioma

Sato, Y., Tomita, M., Soga, T., Ochiai, A., Makinoshima, H.

Front. Pharmacol. 12 718675 2021年09月

研究論文（学術雑誌）, 共著, 査読有り

Malignant pleural mesothelioma (MPM) is an invasive malignancy that develops in the pleural cavity, and antifolates are used as chemotherapeutics for treating. The majority of antifolates, including pemetrexed (PMX), inhibit enzymes involved in purine and pyrimidine synthesis. MPM patients frequently develop drug resistance in clinical practice, however the associated drug-resistance mechanism is not well understood. This study was aimed to elucidate the mechanism underlying resistance to PMX in MPM cell lines. We found that among the differentially expressed genes associated with drug resistance (determined by RNA sequencing), TYMS expression was higher in the established resistant cell lines than in the parental cell lines. Knocking down TYMS expression significantly reduced drug resistance in the resistant cell lines. Conversely, TYMS overexpression significantly increased drug resistance in the parental cells. Metabolomics analysis revealed that the levels of dTMP were higher in the resistant cell lines than in the parental cell lines; however, resistant cells showed no changes in dTTP levels after PMX treatment. We found that the nucleic acid-biosynthetic pathway is important for predicting the efficacy of PMX in MPM cells. The results of chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) assays suggested that H3K27 acetylation in the 5′-UTR of TYMS may promote its expression in drug-resistant cells. Our findings indicate that the intracellular levels of dTMP are potential biomarkers for the effective treatment of patients with MPM and suggest the importance of regulatory mechanisms of TYMS expression in the disease.

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Empagliflozin Maintains Capillarization and Improves Cardiac Function in a Murine Model of Left Ventricular Pressure Overload

Nakao, M., Shimizu, I., Katsuumi, G., Yoshida, Y., Suda, M., Hayashi, Y., Ikegami, R., Hsiao, Y. T., Okuda, S., Soga, T., Minamino, T.

Sci Rep. 11 （ 1 ） 18384 2021年09月

研究論文（学術雑誌）, 共著, 査読有り

Patients with type 2 diabetes treated with Sodium glucose transporter 2 (SGLT2) inhibitors show reduced mortality and hospitalization for heart failure (HF). SGLT2 inhibitors are considered to activate multiple cardioprotective pathways; however, underlying mechanisms are not fully described. This study aimed to elucidate the underlying mechanisms of the beneficial effects of SGLT2 inhibitors on the failing heart. We generated a left ventricular (LV) pressure overload model in C57BL/6NCrSlc mice by transverse aortic constriction (TAC) and examined the effects of empagliflozin (EMPA) in this model. We conducted metabolome and transcriptome analyses and histological and physiological examinations. EMPA administration ameliorated pressure overload-induced systolic dysfunction. Metabolomic studies showed that EMPA increased citrulline levels in cardiac tissue and reduced levels of arginine, indicating enhanced metabolism from arginine to citrulline and nitric oxide (NO). Transcriptome suggested possible involvement of the insulin/AKT pathway that could activate NO production through phosphorylation of endothelial NO synthase (eNOS). Histological examination of the mice showed capillary rarefaction and endothelial apoptosis after TAC, both of which were significantly improved by EMPA treatment. This improvement was associated with enhanced expression phospho-eNOS and NO production in cardiac endothelial cells. NOS inhibition attenuated these cardioprotective effects of EMPA. The in vitro studies showed that catecholamine-induced endothelial apoptosis was inhibited by NO, arginine, or AKT activator. EMPA activates the AKT/eNOS/NO pathway, which helps to suppress endothelial apoptosis, maintain capillarization and improve systolic dysfunction during LV pressure overload.

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Petasin potently inhibits mitochondrial-complex-I-based metabolism that suppors tumor growth and metastasis

Heishima, K., Sugito, N., Soga, T., Nishikawa, M., Ito, Y., Honda, R., Kuranaga, Y., Sakai, H., Ito, R., Nakagawa, T., Ueda, H., Akao, Y.

Clin. Invest. 131 （ 17 ） e139933 2021年09月

研究論文（学術雑誌）, 共著, 査読有り

Mitochondrial electron transport chain complex I (ETCC1) is the essential core of cancer metabolism, yet potent ETCC1 inhibitors capable of safely suppressing tumor growth and metastasis in vivo are limited. From a plant extract screening, we identified petasin (PT) as a highly potent ETCC1 inhibitor with a chemical structure distinct from conventional inhibitors. PT had at least 1700 times higher activity than that of metformin or phenformin and induced cytotoxicity against a broad spectrum of tumor types. PT administration also induced prominent growth inhibition in multiple syngeneic and xenograft mouse models in vivo. Despite its higher potency, it showed no apparent toxicity toward nontumor cells and normal organs. Also, treatment with PT attenuated cellular motility and focal adhesion in vitro as well as lung metastasis in vivo. Metabolome and proteome analyses revealed that PT severely depleted the level of aspartate, disrupted tumor-associated metabolism of nucleotide synthesis and glycosylation, and downregulated major oncoproteins associated with proliferation and metastasis. These findings indicate the promising potential of PT as a potent ETCC1 inhibitor to target the metabolic vulnerability of tumor cells.

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High-throughput screening of salivary polyamine markers for discrimination of colorectal cancer by multisegment injection capillary electrophoresis tandem mass spectrometry

Igarashi K., Ota S., Kaneko M., Hirayama A., Enomoto M., Katumata K., Sugimoto M., Soga T.

J. Chromatogr. A. 1652 462355 2021年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00219673

Polyamine metabolites provide pathophysiological information on disease or therapeutic efficacy, yet rapid screening methods for these biomarkers are lacking. Here, we developed high-throughput polyamine metabolite profiling based on multisegment injection capillary electrophoresis triple quadrupole tandem mass spectrometry (MSI-CE-MS/MS), which allows sequential 40-sample injection followed by electrophoretic separation and specific mass detection. To achieve consecutive analysis of polyamine samples, 1 M formic acid was used as the background electrolyte (BGE). The BGE spacer volume had an apparent effect on peak resolution among samples, and 20 nL was selected as the optimal volume. The use of polyamine isotopomers as the internal standard enabled the correction of matrix effects in MS detection. This method is sensitive, selective and quantitative, and its utility was demonstrated by screening polyamines in 359 salivary samples within 360 min, resulting in discrimination of colorectal cancer patients from noncancer controls.

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Targeting Amino Acid Metabolic Reprogramming via L-Type Amino Acid Transporter 1 (LAT1) for Endocrine-Resistant Breast Cancer

Shindo, H., Harada-Shoji, N., Ebata, A., Sato, M., Soga, T., Miyashita, M., Tada, H., Kawai, M., Kosaka, S., Onuki, K., Usami, S., Furumoto, S., Hayashi, S., Abe, T., Suzuki, T., Ishida, T., Sasano, H.

Cancers 13 （ 17 ） 4375 2021年08月

研究論文（学術雑誌）, 共著, 査読有り

The PI3K/Akt/mTOR pathway has been well known to interact with the estrogen receptor (ER)-pathway and to be also frequently upregulated in aromatase inhibitor (AI)-resistant breast cancer patients. Intracellular levels of free amino acids, especially leucine, regulate the mammalian target of rapamycin complex 1 (mTORC1) activation. L-type amino acid transporters such as LAT1 and LAT3 are associated with the uptake of essential amino acids. LAT1 expression could mediate leucine uptake, mTORC1 signaling, and cell proliferation. Therefore, in this study, we explored amino acid metabolism, including LAT1, in breast cancer and clarified the potential roles of LAT1 in the development of therapeutic resistance and the eventual clinical outcome of the patients. We evaluated LAT1 and LAT3 expression before and after neoadjuvant hormone therapy (NAH) and examined LAT1 function and expression in estrogen deprivation-resistant (EDR) breast carcinoma cell lines. Tumors tended to be in advanced stages in the cases whose LAT1 expression was high. LAT1 expression in the EDR cell lines was upregulated. JPH203, a selective LAT1 inhibitor, demonstrated inhibitory effects on cell proliferation in EDR cells. Hormone therapy changed the tumor microen-vironment and resulted in metabolic reprogramming through inducing LAT1 expression. LAT1 expression then mediated leucine uptake, enhanced mTORC1 signaling, and eventually resulted in AI resistance. Therefore, LAT1 could be the potential therapeutic target in AI-resistant breast cancer patients.

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An extensive and dynamic trans-omic network illustrating prominent regulatory mechanisms in response to insulin in the liver

Matsuzaki, F., Uda, S., Yamauchi, Y., Matsumoto, M., Soga, T., Maehara, K., Ohkawa, Y., Nakayama, K., Kuroda, S., Kubota, H.

Cell Rep. 36 （ 8 ） 109569 2021年08月

研究論文（学術雑誌）, 共著, 査読有り

An effective combination of multi-omic datasets can enhance our understanding of complex biological phenomena. To build a context-dependent network with multiple omic layers, i.e., a trans-omic network, we perform phosphoproteomics, transcriptomics, proteomics, and metabolomics of murine liver for 4 h after insulin administration and integrate the resulting time series. Structural characteristics and dynamic nature of the network are analyzed to elucidate the impact of insulin. Early and prominent changes in protein phosphorylation and persistent and asynchronous changes in mRNA and protein levels through non-transcriptional mechanisms indicate enhanced crosstalk between phosphorylation-mediated signaling and protein expression regulation. Metabolic response shows different temporal regulation with transient increases at early time points across categories and enhanced response in the amino acid and nucleotide categories at later time points as a result of process convergence. This extensive and dynamic view of the trans-omic network elucidates prominent regulatory mechanisms that drive insulin responses through intricate interlayer coordination.

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Amino acid transporters as emerging therapeutic targets in cancer

Saito Y., Soga T.

Cancer Sci. 112 （ 8 ） 2958 - 2965 2021年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13479032

Amino acids are indispensable nutrients for both normal and cancer cells. Cancer cells are unable to synthesize essential amino acids as well as some non-essential amino acids adequately to support rapid proliferation, and must take up amino acids from the surroundings. To meet the increased demand for the amino acid needed for proliferation, high levels of amino acid transporters are expressed on the surface of cancer cells. Cancer cells utilize amino acids to synthesize proteins and nucleotides, as well as to obtain energy. In addition, amino acids are known to play pathological roles in cancer cells. Interestingly, breast cancer cells limit the use of amino acids for cell proliferation based on amino acid availability, which depends on estrogen receptor status. Here, we present a summarized literature review of novel amino acid functions in cancer cells. This review organizes the available knowledge on 2 amino acid transporters, SLC7A5 and SLC7A11, which are considered essential for breast cancer cell growth in a cell-dependent manner. In particular, we propose the glutamine recycling model to clarify the mechanism underlying aberrant SLC7A5 activation. Finally, we overview the pathological significances of SLC7A5 and SLC7A11 in cancer tissues.

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The CD44/COL17A1 pathway promotes the formation of multilayered, transformed epithelia

Kozawa, K., Sekai, M., Ohba, K., Ito, S., Sako, H., Maruyama, T., Kakeno, M., Shirai, T., Kuromiya, K., Kamasaki, T., Kohashi, K., Tanaka, S., Ishikawa, S., Sato, N., Asano, S., Suzuki, H., Tanimura, N., Mukai, Y., Gotoh, N., Tanino, M., Tanaka, S., Natsuga, K., Soga, T., Nakamura, T., Yabuta, Y., Saitou, M., Ito, T., Matsuura, K., Tsunoda, M., Kikumori, T., Iida, T., Mizutani,Y., Miyai, Y., Kaibuchi, K., Enomoto, A., Fujita, Y.

Curr. Biol. 31 （ 14 ） 3086 - 3097 2021年07月

研究論文（学術雑誌）, 共著, 査読有り

At the early stage of cancer development, oncogenic mutations often cause multilayered epithelial structures. However, the underlying molecular mechanism still remains enigmatic. By performing a series of screenings targeting plasma membrane proteins, we have found that collagen XVII (COL17A1) and CD44 accumulate in RasV12-, Src-, or ErbB2-transformed epithelial cells. In addition, the expression of COL17A1 and CD44 is also regulated by cell density and upon apical cell extrusion. We further demonstrate that the expression of COL17A1 and CD44 is profoundly upregulated at the upper layers of multilayered, transformed epithelia in vitro and in vivo. The accumulated COL17A1 and CD44 suppress mitochondrial membrane potential and reactive oxygen species (ROS) production. The diminished intracellular ROS level then promotes resistance against ferroptosis-mediated cell death upon cell extrusion, thereby positively regulating the formation of multilayered structures. To further understand the functional role of COL17A1, we performed comprehensive metabolome analysis and compared intracellular metabolites between RasV12 and COL17A1-knockout RasV12 cells. The data imply that COL17A1 regulates the metabolic pathway from the GABA shunt to mitochondrial complex I through succinate, thereby suppressing the ROS production. Moreover, we demonstrate that CD44 regulates membrane accumulation of COL17A1 in multilayered structures. These results suggest that CD44 and COL17A1 are crucial regulators for the clonal expansion of transformed cells within multilayered epithelia, thus being potential targets for early diagnosis and preventive treatment for precancerous lesions.

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De novo deoxyribonucleotide biosynthesis regulates cell growth and tumor progression in small-cell lung carcinoma

Maruyama A., Sato Y., Nakayama J., Murai J., Ishikawa T., Soga T., Makinoshima H.

Sci. Rep. 11 （ 1 ） 13474 2021年06月

研究論文（学術雑誌）, 共著, 査読有り

Deoxyribonucleotide biosynthesis from ribonucleotides supports the growth of active cancer cells by producing building blocks for DNA. Although ribonucleotide reductase (RNR) is known to catalyze the rate-limiting step of de novo deoxyribonucleotide triphosphate (dNTP) synthesis, the biological function of the RNR large subunit (RRM1) in small-cell lung carcinoma (SCLC) remains unclear. In this study, we established siRNA-transfected SCLC cell lines to investigate the anticancer effect of silencing RRM1 gene expression. We found that RRM1 is required for the full growth of SCLC cells both in vitro and in vivo. In particular, the deletion of RRM1 induced a DNA damage response in SCLC cells and decreased the number of cells with S phase cell cycle arrest. We also elucidated the overall changes in the metabolic profile of SCLC cells caused by RRM1 deletion. Together, our findings reveal a relationship between the deoxyribonucleotide biosynthesis axis and key metabolic changes in SCLC, which may indicate a possible link between tumor growth and the regulation of deoxyribonucleotide metabolism in SCLC.

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